U.S. Pat. Nos. 3,207,077 and 4,386,891, issued Sep. 21, 1965 and Jun. 7, 1983, respectively, and assigned to the assignee of this invention, describe motor vehicle power steering hydraulic pumps having flow control valves which recirculate a varying fraction of the discharge of a positive displacement rotating group of the pump to an inlet of the rotating group as the speed of the rotating group increases. The flow control valves include a valve spool which opens and closes a recirculation flow path of the pump in accordance with a pressure gradient across the valve spool proportional to flow rate. A relief pressure of the pump depends upon a force reaction or preload of a spring on the valve spool against a relief valve element on the valve spool. While such force reaction is easily established within close tolerance outside of the pump, relief pressures actually achieved have been observed to vary within a relatively broad range due to the accumulation of manufacturing tolerances within pumps. Reducing such manufacturing tolerances to correspondingly reduce the range of relief pressure variation increases the cost of manufacturing power steering pumps.